案例2：⽤⼀条SQL查询出数学语⽂成绩都⼤于80分的学⽣姓
输入姓名查询成绩在线名？
⽅法1：
查出科⽬成绩有⼩于80分的学⽣姓名，再约束并去重学⽣不等于查出来的姓名
select distinct A.name from t_score A where A.name not in(select distinct B.name from t_score B where B.fenshu <=80)
⽅法2：
按学⽣姓名分组，且最⼩的分数要⼤于80分
select A.name from t_score A group by A.name having min(A.fenshu)>80